The technical field of the present invention relates generally to telecommunication networks and, more particularly, to the integration of a centralized network restoration system with a distributed network restoration system.
Telecommunication networks, such as telephone networks, are subject to failure. Given the volume of traffic and the criticality of some of the traffic on such telecommunication networks, it is desirable to be able to restore from failures as quickly as possible. In general, restoration from a failure involves the following four steps: (1) detecting that a failure has occurred; (2) isolating the location of the failure within the network; (3) determining a restoral route that may be used by network traffic; (4) implementing the restoral route.
Approaches for restoring a telecommunications network are generally classified as either being dynamic or static. The static restoration approaches develop xe2x80x9cpre-plansxe2x80x9d for restoring a telecommunications network. The xe2x80x9cpre-plansxe2x80x9d are developed by simulating possible network failures and determining restoral routes to restore the network from the simulated network failures. The xe2x80x9cpre-plansxe2x80x9d are generally developed for a given segment of a network that can incur failure. When a segment fails, the associated xe2x80x9cpre-planxe2x80x9d is utilized.
Dynamic restoration approaches dynamically determine restoral routes at the time of failure. The dynamic restoration approaches perform analysis of the telecommunications network at the time of failure to generate the restoral routes. Dynamic restoration approaches generally fall into two categories: centralized restoration methods and distributed restoration methods. With centralized restoration methods, a centralized computer system is responsible for receiving alarms that indicate a failure has occurred, performing analysis to isolate the location of the failure, determining an optimal restoral route and sending commands to implement the restoral route. Distributed restoration methods use the network nodes as the active agents for performing restoration. When the nodes detect a failure, they search for a restoral route by sending messages to each other and attempting various links of potential restoral routes. The distributed restoration methods have the advantage of being faster than the centralized restoration methods; however, not all failures may be resolved and restored by distributed restoration methods. Some nodes of the network are not capable of performing distributed restoration.
The present invention addresses the limitations of the prior art by integrating a centralized restoration system with a distributed restoration system. The centralized restoration system is a single computer system for restoring the network from failure, whereas the distributed restoration system is distributed among restoration nodes of the network. When a failure occurs in the network, the system will generally attempt to restore the network using the distributed restoration system. If the distributed restoration system fails to restore the network, the centralized restoration system may be utilized. In some instances, the distributed restoration system will be successful and the centralized restoration system need not be utilized.
The network may include trunks that interconnect the nodes so that the nodes may communicate with each other. Trunks may be assigned to the centralized restoration system or the distributed restoration system. When a trunk is assigned to the centralized restoration system, the restoration is performed by the centralized restoration system. In the case where a trunk is assigned to the distributed restoration system, the distributed restoration system first attempts to determine and implement a restoral route for the failure and then, if unsuccessful, asks for assistance from the centralized restoration system.
In general, the distributed restoration system may be first invoked to attempt to restore from a network failure. The distributed restoration system may more quickly restore higher priority portions of the network than the centralized restoration system. The distributed restoration system may then subsequently communicate with the centralized restoration system to indicate whether assistance is required from the centralized restoration system.